Reply
 
Thread Tools Search this Thread Display Modes
 
Old 10-18-2012, 07:55 AM   #99
Rivet Master
 
dznf0g's Avatar

 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 9,403
Images: 5
Quote:
Originally Posted by purman View Post
I'm running around 4900-5000 dry. So yes well under the max rating. The 4psi raise I figure they must take into account even if you start at the max psi and go over. I don't want to run max psi as it is overkill for the weight of my AS. And may beat it up going down the road. I don't think you can hurt anything to much running them at max psi, but if your AS is well under the max rating of the tires you will give the AS a hard ride.
I agree Jason, I believe (what I am trying to figure out) is that there is a proper pressure rise, for each tire size/brand/type, where that rise will be 4 PSI, (again, under my climate, geography, and speed).

My THEORY, and only a theory at this point, is that the automakers do EXTENSIVE validation testing on tires and the behavior we can note with TPMS vs. load. vs speed, etc., we should be able to translate over to the AS where we are deviating form OEM tires and be able to answer these nagging proper pressure questions. (How's that for a run on sentance?)

I think that (especially those of you with lighter rigs) can find that 4 psi mark, and reduce pressure till you see a rise greater than that, then back up to the pressure where you just see 4 psi (or your number for your climate, speed.....that you normally see on your properly inflated TV). At least you will be running the temps that an OEM automaker has deemed good to go. That's a lot more than we have to go on with our AS questions.

I just haven't found it yet on my rig...and I am not sure why, based on the info above.
__________________

__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is offline   Reply With Quote
Old 10-18-2012, 08:22 AM   #100
Rivet Master
 
dznf0g's Avatar

 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 9,403
Images: 5
I have an Excel chart using the ideal gas formula that calculates the temperature rise based on the pressure rise - and the pecent rule works. 10% - whether you start at 30 psi (and get a 3 psi buildyp) or at 70 psi (and get a 7 psi buildup) results in very simlar temperature buildups.


OK, I agree with your RELEVANT TO THIS DISCUSSION parts, (won't argue the other stuff, other than to say, I underwent significant training during the Ford/Firestone thing, and, at least at that time, there were SIGNIFICANT differences in the way MFRS tested, "certified" and selected tires.)

I am, however, confused by this statement. I had always understood, and TireRack states (for whatever that is worth) that the correlation is 1psi = 10 degrees, irrespective of the starting pressure.

Are you saying that if I find a pressure where I see (consistently) 7 psi rise at 70psi cold, that I will be running the same temperature as a theoretical tire seeing a 3psi rise at 30 psi. (disregard construction variables, etc., just based on gas thoery)

Tire Tech Information - Air Pressure, Temperature Fluctuations
__________________

__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is offline   Reply With Quote
Old 10-18-2012, 09:27 AM   #101
Rivet Master
 
dznf0g's Avatar

 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 9,403
Images: 5
I posted this over on a TPMS thread. Maybe this will explain why I am so adimate about this subject....or not

"Guys, I'm not trying to be arnry, nor am I trying to say that TPMS temps are no good. I am saying that I have found noplace where I can find a correlation between the reading and what actual temps are where it matters, at the shoulders and across the tread ON THE INSIDE, where the bonding of tire components are.

Measuring the sidewall (where???) may very well match the air temp in the valve stem, but how do those temps correlate to the temp at the shoulder...and what is your baseline for accepting your readings elsewhere as normal? And what IS normal at the shoulder? The only readings I can find concern NASCAR and on Hoosier tire site refering to racing tires and conditions. Not a good comparison.

See the graphic below: The temps of the middle of the sidewwall don't change much, but they claim that 14* can make a difference at the shoulder??????? These are questions.....I don't have the answer, but we need a baseline for normal, regardless of how or where we measure."

Click image for larger version

Name:	thermal_heat.jpg
Views:	55
Size:	98.6 KB
ID:	170687
__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is offline   Reply With Quote
Old 10-18-2012, 09:27 AM   #102
Rivet Master
 
purman's Avatar
 
1968 28' Ambassador
Cedaredge , Colorado
Join Date: Jul 2008
Posts: 2,542
Quote:
Originally Posted by dznf0g

I agree Jason, I believe (what I am trying to figure out) is that there is a proper pressure rise, for each tire size/brand/type, where that rise will be 4 PSI, (again, under my climate, geography, and speed).

My THEORY, and only a theory at this point, is that the automakers do EXTENSIVE validation testing on tires and the behavior we can note with TPMS vs. load. vs speed, etc., we should be able to translate over to the AS where we are deviating form OEM tires and be able to answer these nagging proper pressure questions. (How's that for a run on sentance?)

I think that (especially those of you with lighter rigs) can find that 4 psi mark, and reduce pressure till you see a rise greater than that, then back up to the pressure where you just see 4 psi (or your number for your climate, speed.....that you normally see on your properly inflated TV). At least you will be running the temps that an OEM automaker has deemed good to go. That's a lot more than we have to go on with our AS questions.

I just haven't found it yet on my rig...and I am not sure why, based on the info above.
One problem is if you change climate you have to change tire pressure. I live at 7000 ft and can change climate in 20 min and again in 1 hour or less depending which way I drive. . I don't want to have to change my psi while traveling so I am finding that happy medium. This is my first trip with the new tires and I may lower the psi back down to 60 psi on the way home and see if there is a difference in ride or psi gain and temp. I will let you know.
__________________
Jason

May you have at least one sunny day, and a soft chair to sit in..

2008 5.7 L V8 Sequoia
AIR # 31243
WBCCI # 6987
FOUR CORNERS UNIT
purman is offline   Reply With Quote
Old 10-18-2012, 09:33 AM   #103
Rivet Master
 
dznf0g's Avatar

 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 9,403
Images: 5
Quote:
Originally Posted by purman View Post
One problem is if you change climate you have to change tire pressure. I live at 7000 ft and can change climate in 20 min and again in 1 hour or less depending which way I drive. . I don't want to have to change my psi while traveling so I am finding that happy medium. This is my first trip with the new tires and I may lower the psi back down to 60 psi on the way home and see if there is a difference in ride or psi gain and temp. I will let you know.
Agreed. your baseline pressure will always need to be adjusted due to weather and other environmental conditions. When and how much to compensate is each of our choices.
__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is offline   Reply With Quote
Old 10-18-2012, 10:00 AM   #104
Rivet Master
 
dznf0g's Avatar

 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 9,403
Images: 5
Well, I found something. Have no idea as to the credibility of this read. Capriracer....care to share your knowledge as to these temps and how we may interpret them using infrared on the outside of the tire shoulder and using TPMS (both the pressure rise method and stem air temp method)?

Why Temperature?

(is there an error in #2 sub section 3? Shouldn't those be Ferenheit figures, not Celcius?)
__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is offline   Reply With Quote
Old 10-18-2012, 11:23 AM   #105
Rivet Master
 
mefly2's Avatar
 
2015 25' FB Eddie Bauer
Western , ** Big Sky Country ** Montana
Join Date: Feb 2010
Posts: 2,283
Quote:
Originally Posted by A W Warn View Post
I read the things you posted from the Silverado Owner's Manual. I have been driving 1500 Chevy trucks for the last 30 years or more. I have about 1,000 miles on my first 2500. (always drove Fords before) What I noticed early on about the tires on the Chevys, especially on the 4 wheel drives, was the tires always were worn more on the outer edges before the end of the tread life at the center of the tire. Balance or alignment was not the problem. After many sets worn this way over the years, on the advice of a friend, I started adding about 5 PSI above what was on the door placard. (still below the max psi on the sidewall) Once I started doing this I always got even wear and an extra 5 or 10,000 miles on the tires. The ride was better too. I'm a believer in this, and will continue to do so.
My experience is in agreement with AWW - if the tires are uniformly worn on both outer edges of a single tire (front or rear), more pressure is needed for even wear. If, however, (as is most visible on 4wd lugged front tires) there is wear only on the outside or inside edge of a single tire, it is most likely an alignment problem. In several other threads, issues have arisen about uneven tire wear on the TT. Isn't out of alignment another source of heat / rise in tire pressure? I have been told that misalignment of TT axles is mostly over looked.
__________________
mefly2 is offline   Reply With Quote
Old 10-18-2012, 11:25 AM   #106
Rivet Master
 
dznf0g's Avatar

 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 9,403
Images: 5
Quote:
Originally Posted by mefly2 View Post
My experience is in agreement with AWW - if the tires are uniformly worn on both outer edges of a single tire (front or rear), more pressure is needed for even wear. If, however, (as is most visible on 4wd lugged front tires) there is wear only on the outside or inside edge of a single tire, it is most likely an alignment problem. In several other threads, issues have arisen about uneven tire wear on the TT. Is out of alignment another source of heat / rise in tire pressure?
Certainly, scrubbing will raise temperature.

http://www.infraredimagingservices.com/left-tire

This is a great reason to carry a infrared thermometer and measure across the tread face; right center and left.
__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is offline   Reply With Quote
Old 10-18-2012, 11:33 AM   #107
CapriRacer
 
CapriRacer's Avatar
 
I'm in the , US
Join Date: Sep 2012
Posts: 624
Quote:
Originally Posted by dznf0g View Post
......I am, however, confused by this statement. I had always understood, and TireRack states (for whatever that is worth) that the correlation is 1psi = 10 degrees, irrespective of the starting pressure.....
That only applies to passenger car tires.

Yes, yes, I know. Tire Rack doesn't say that - but they should!

Again, up to a 10% rise in pressure is OK regardless of the starting pressure. (and I checked with some other extreme tire pressures - like 300 psi for aircraft - and it works there as well.
__________________
CapriRacer is offline   Reply With Quote
Old 10-18-2012, 11:39 AM   #108
Rivet Master
 
richinny's Avatar
 
2011 34' Classic
Westchester Cty.NY , / Miami FL
Join Date: Jul 2007
Posts: 3,122
dznf0g

since you've got such an interest in tire pressure i was wondering if you've tried filling the tires with nitrogen? your customary detailed reporting would give it a lot of credibility.
__________________
Ricky
2012 F150 Super Crew 5-1/2' bed Ecoboost 4x4 3.73 elec. lock diff. Propride hitch
give life. kidney & pancreas transplant 9/9/06
Ingrid-my unofficial '"World's Oldest Streamer" 1909-2008 R.I.P.
richinny is offline   Reply With Quote
Old 10-18-2012, 12:10 PM   #109
Rivet Master
 
dznf0g's Avatar

 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 9,403
Images: 5
Quote:
Originally Posted by CapriRacer View Post
That only applies to passenger car tires.

Yes, yes, I know. Tire Rack doesn't say that - but they should!

Again, up to a 10% rise in pressure is OK regardless of the starting pressure. (and I checked with some other extreme tire pressures - like 300 psi for aircraft - and it works there as well.
OK! finally! So when I find that point where 10% is met, I have arrived?

For example:

65psi with 7 - 9 rise is a little low
70psi with 7 - 9 rise ....maybe...

If I try and see

75psi with, say 7 - 8 psi rise is perfect.

FYI, I did find a site (upthread) that says 1 psi/10 degrees for passenger tires

and

2 psi/10 degrees for "truck and RV tires"
But it was a class 7/8/9 truck tire site. What do they consider LTs? Passenger or "truck" ?
__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is offline   Reply With Quote
Old 10-18-2012, 12:35 PM   #110
Rivet Master
 
dznf0g's Avatar

 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 9,403
Images: 5
Capri, Could you provide any insight on the questions in post #101?
__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is offline   Reply With Quote
Old 10-18-2012, 01:59 PM   #111
CapriRacer
 
CapriRacer's Avatar
 
I'm in the , US
Join Date: Sep 2012
Posts: 624
Quote:
Originally Posted by dznf0g View Post
OK! finally! So when I find that point where 10% is met, I have arrived?....
No, no, no. The 10% should be considered a maximum before action is taken - not a target. In street tires, cooler is always better.

Oh, and those other posts that folks have been requesting comment on - I'd like to think about those a bit. I'll comment later.
__________________
CapriRacer is offline   Reply With Quote
Old 10-18-2012, 02:04 PM   #112
Rivet Master
 
dznf0g's Avatar

 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 9,403
Images: 5
Quote:
Originally Posted by CapriRacer View Post
No, no, no. The 10% should be considered a maximum before action is taken - not a target. In street tires, cooler is always better.

Oh, and those other posts that folks have been requesting comment on - I'd like to think about those a bit. I'll comment later.

So what is the target on LTs, if they are different than P metrics?

And.... why is it common and normal to see a p metric with a 4 psi rise and a cold pressure of 35psi per the placard with no load in the bed running solo?

Sumptins' sqwuee, again.

What am I missing?
__________________

__________________
-Rich-

"If the women don't find you handsome, they should at least find you handy." - Red Green
dznf0g is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Safe Tire Pressure Morgan guy Tires 165 01-10-2013 01:49 PM
02/12: New Tire Discussion on Woodalls: LT versus ST and more. slowmover Tires 128 04-10-2012 06:09 PM
Putting a safe in 2012 27' FB Int Jordanparson General Interior Topics 5 02-24-2012 11:33 PM
Bolt pattern & tire size for 68' Ambassador silverwoman Wheels, Hubs & Bearings 3 02-16-2012 10:36 PM


Virginia Campgrounds

Reviews provided by




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 02:44 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.